As compared to active devices, such as transistors for logic and memory, passive devices are used in electronic devices to transform, smooth, and balance electrical and radio signals. They are used in power supplies, transmitters, sensors, reference signal sources, timing circuits, and a wide range of other systems and circuits. A silicon die is typically made of materials and using processes that are optimized for active devices. With millions of active transistors on a device, a designer may simulate a capacitor or resistor using modified transistors or diodes rather than form a poor performance version of such a device in the silicon die.
With increasing mobility, electronic devices are designed to incorporate radio components and batteries and also be more compact for portability. This means that the extra space required for quality passive devices becomes a more significant obstacle to miniaturization. Integrated Passive Devices (IPD) are seen as a technology for reducing the impact of passive devices on overall product size. IPDs are attracting an increasing interest in mobile devices like phones and tablets. IPDs help to further decrease the size and cost of a product and increase the functionality and performance of those devices.
Classical IPD components are produced on silicon material. Thin film technology, e.g. sputtering, electroplating, and spin-coating, is typically used to generate the passive structures. IPDs can be made as coils, capacitors (high-density trench capacitors, MIM capacitors), high-Q inductors, resistors, baluns, filters, PIN diodes or Zener diodes and still more types of devices which can all be built in a single silicon component.